| knotty(adjective, hard, tough, severe, rough) |
| merciless(adjective, tough, rough, difficult, heavy) |
| operose(adjective, tough, severe, difficulty, difficult) |
| overpowering(adjective, difficult, tiring) |
| rigorous(adjective, hard, severe, rough, difficult) |
| rough(adjective, hard, great, tough, severe) |
| serious(adjective, hard, tough, severe, rough) |
| tedious(adjective, dull, difficult, boring, demanding) |
| time-consuming(adjective, hard, tough, difficult, slow) |
| tiresome(adjective, hard, severe, difficult, heavy) |
| wearing(adjective, dull, hard, tough, difficult) |
| complicated(adjective, hard, tough, severe, rough) |
| galling(adjective, tough, severe, difficult, heavy) |
| grueling(adjective, hard, tough, difficult, heavy) |
| intolerable(adjective, difficult, tiring) |
| unwieldy(adjective, awkward, bulky) |
| back-breaking |
| complex(adjective, difficult) |
| cumbrous(pain, hindrance) |
| excessive(adjective, difficult, tiring) |